Method and Tool for Producing Sheet Metal Components

ABSTRACT

A method for producing sheet metal components is disclosed. The method includes preshaping a workpiece to form a preshaped component. Excess material is introduced into the preshaped component at least in regions. The method includes, calibrating the preshaped component to form an at least partially finally shaped component using the excess material. The preshaped component is compressed at least in sections. The method achieves high dimensional accuracy, rigidity and/or hardening of components. According to one aspect of the method, different regions of the preshaped component are calibrated in a time-staggered manner, or one or more locally thickened region are produced during the calibration.

The present invention relates, according to different aspects, to methods for producing sheet metal components, the methods each comprising: preshaping a workpiece to form a preshaped component, wherein material which is excess at least in regions is introduced into the preshaped component; and calibrating the preshaped component to form an at least partially finally shaped component using the excess material, wherein the preshaped component is compressed at least in sections. In addition, the invention relates, according to the different aspects, to tools for producing sheet metal components, in particular for carrying out the method according to the invention of the respective aspect, comprising: at least one preshaping tool for preshaping a workpiece to form a preshaped component, wherein material which is excess at least in regions is introduced into the preshaped component; and at least one calibrating tool for calibrating the preshaped component to form an at least partially finally shaped component using the excess material, wherein the preshaped component is compressed at least in sections.

Components produced by sheet metal shaping, in particular deep drawn components, generally require final edge trimming, in which excess regions of the, for example, deep-drawn component are cut off. In the case of parts having flanges, this can take place, for example, by means of one or more trimming tools which partially or entirely trim the flange from above or obliquely in the desired manner. In the case of flangeless parts, by contrast, the trimming is already substantially more complicated because it has to be cut off from the side, for example guided via cam sliders. Trimming operations of this type are, however, disadvantageous in so far as the trimming generally requires one or even more separate operations which also frequently require dedicated tool technology and a dedicated logistics system. In addition, the cut-off regions increase the proportion of scrap, as a result of which further costs arise. For example, in the case of components which are formed by means of turning on edge or stamping, the final edge trimming can also be omitted.

In order to at least shorten the process chain, different approaches have been pursued with which, inter alia, the flange trimming has been integrated into the final shaping operation, for example deep drawing operation. Therefore, although significant cost savings can already be obtained, some disadvantages still remain, such as, for example, the production of trimmed waste, the construction of complicated tools, complex testing, undesirable springback effects, limited dimensional accuracy and susceptibility to process malfunctions.

For this reason, methods and tools have been proposed in order to save or to greatly reduce the edge trimming of in particular U-shaped or hat-profile-like components.

German laid-open application DE 10 2007 059 251 A1 thus describes a method for producing highly dimensionally accurate, deep drawn half shells with a base region and a wall with little outlay on apparatus. For this purpose, first of all a preshaped half shell is formed from a blank. The entire cross section of the preshaped half shell comprises excess blank material because of its geometrical shape. During the deformation of the preshaped half shell into its final shape by means of at least one further pressing operation, the entire cross section is compressed to form the finished half shell, and the finished half shell has an increased wall thickness over the entire cross section.

German laid-open application DE 10 2008 037 612 A1 likewise describes a method for producing highly dimensionally accurate, deep drawn half shells with a base region, a wall region and a flange region, wherein a preshaped shell is first of all produced from a blank and is subsequently deformed to form the finally shaped half shell. The preshaped half shell has excess blank material because of its geometrical shape. During the deformation of the preshaped half shell into its final shape by means of at least one further pressing process, the excess material enables the half shell to be compressed to form the finally shaped half shell. The preshaped half shell comprises the excess blank material in the transition region between wall region and flange region.

German laid-open application DE 10 2009 059 197 A1 describes a method for producing a half shell part using a drawing punch and a drawing die. Reliable and cost-effective production is achieved in that, in a single working step, the drawing punch is retracted into the drawing die, a blank is preshaped to form a sheet metal unmachined part with at least one base portion, at least one wall portion and optionally a flange portion, wherein, during the preshaping with the drawing punch, excess material is introduced either into the base portion and the wall portion or into the optional flange portion of the sheet metal unmachined part, and the sheet metal unmachined part is finally shaped to form a half shell part and calibrated.

German laid-open application DE 10 2013 103 612 A1 likewise describes a method for producing highly dimensionally accurate, deep drawn half shells, wherein a half shell which is preshaped from a blank is deformed to form a finished half shell, and the preshaped half shell comprises excess blank material because of its geometrical shape. The half shell is compressed in a compression tool to form the finally shaped half shell. It is provided that the size of the compression gap is reduced to the actual wall strength of the wall of the preshaped half shell while the compression tool is closed.

German laid-open application DE 10 2013 103 751 A1 discloses a method for producing highly dimensionally accurate half shells from a trimmed blank, wherein the half shell is preshaped in a first die by deep drawing, and wherein the preshaped half shell is subsequently finally shaped in a second die, in particular in a calibration tool. The blank is trimmed, taking into consideration the desired final shape of the preshaped or finally shaped half shell, prior to the deep drawing with a positive dimensional deviation within the predetermined tolerance range, and the die base of the first die is moved relative to the die rest surface in order to deep draw the blank in a guided manner.

A common feature of the described approaches is that, in a first method step or in a plurality of (first) method steps, a preliminary shape is produced which, although it is as close as possible to the final shape or finished shape of the component, it has the difference that defined material reserves are introduced in the component portions, such as flange, wall, transition region between flange and wall and/or base, said material reserves being shaped again in a second method step by specific compression of the entire part during the calibration.

Although this known method eliminates the abovementioned disadvantage, it itself has undesirable side effects. The compression of the preshaped component, particularly in the case of large or heavily stepped parts, large wall thicknesses or/and high-strength steels, requires very high pressing forces which may exceed existing pressing capacities. In addition, high pressing forces can reduce the service life of tools. If these circumstances occur, the abovementioned use of the method has hitherto had to be dispensed with. Furthermore, it has turned out that the local sheet metal thicknesses can also be changed by the compression operation. This gives rise to ripples which may constitute a visual defect. Previous endeavors have been focused on reducing the compression proportions as far as possible, but this is also to the detriment of the component quality with respect to the shape deviation due to springback.

Vehicle structural parts frequently have to absorb high loads and energies. High loads generally require high flexural and buckling rigidities while high energies also require high material strengths. In order to comply with these requirements, in particular if no compression operation is possible, recourse if made, for example, to tailored blanks, patch regions or to tailored tempering, or to special cross-sectional configurations. However, a characteristic of all of these measures is a relatively high outlay including on associated costs. Tailored blanks and patched blanks thus have to be welded and deformed at the same time. Tailored tempering requires heating and the corresponding tempering working step, while special cross sections have to pass through complicated simulations.

Taking this prior art as the starting point, it is the object of the present invention to specify methods and tools with which high dimensional accuracy, rigidity and/or hardening of components can be achieved with little outlay in terms of process technology, in particular in the case of large, partially stepped components and/or materials having high strength and/or a large wall thickness.

According to a first aspect of the present invention, the object is achieved in the case of a method of the type in question in that different regions of the preshaped component are calibrated in a time-staggered manner, or only one or more portions of the preshaped component are calibrated.

Different regions of the preshaped component are therefore at least partially not calibrated at the same time. The different regions can partially overlap or can be entirely different regions. Different regions of the preshaped component are therefore at least partially individually or separately calibrated. The calibration is composed in particular of partial calibration steps. Calibration of a region preferably begins only when the calibration of the previous region has finished. However, it is likewise possible for there to be a partial temporal overlap between the calibration of different regions. For example, at least a first region and a second region are provided which are calibrated in a time-staggered manner. However, more than two (for example three, four, five or more) different regions can also be provided. It is not required here for the entire component, but rather just one or more portions of the preshaped component, to be calibrated. In particular, for geometrically noncritical regions, the calibration can be at least partially dispensed with. That is to say, the preshaped component is not completely calibrated.

The effect achieved by time-staggered calibration of different regions is that components which were hitherto not accessible or not accessible to a sufficient extent for a calibration step because of a high power requirement can now nevertheless be calibrated in such a manner that sufficient hardening can be achieved. Disadvantages mentioned at the beginning can therefore be eliminated or at least greatly minimized, and the spectrum of use can be extended to components which, in particular with the boundary conditions of the method known from the prior art, have hitherto been unable to be manufactured.

The workpiece is, for example, a substantially flat blank. The workpiece is preferably produced from one or more steel materials. Alternatively, aluminum materials or other metals which can be shaped can also be used.

The production of the preliminary shape can be produced in one or more steps by means of shaping methods which can be combined as desired. The preshaping can comprise, for example, a shaping step in the manner of deep drawing. Also possible in particular is multi-stage shaping, comprising, for example, stamping of the base to be constructed and raising of the walls to be constructed or optionally depositing the flanges to be constructed. Any desired combinations of chamfering and/or (embossing) stamping are also conceivable. The preshaped component obtained by preshaping can be considered in particular as a component which is close to the final shape and corresponds as readily as possible to the intended finished part geometry taking into consideration provided boundary conditions, such as spring back and deformation capability of the material used.

The calibration can be understood as meaning in particular final shaping of the preshaped component, which can be achieved, for example, by means of a pressing operation. The finally shaped component can be understood in this respect as a substantially finished component. However, it is possible for the finally shaped component to also be subject to further processing steps modifying the component, such as introducing connection holes. However, it is endeavored to configure the calibration mold in such a manner that no further shaping steps are necessary.

According to a preferred refinement of the invention according to the first aspect, the component is a component in the shape of a half shell, in particular a cross-sectionally U-shaped or hat-shaped component, wherein, for example, an L-shaped cross-sectional shape with just one distinct wall is also possible. For example, the component comprises a base region, a wall region and/or a flange region. For example, the component is a flangeless component at least in regions or comprises a flange at least in regions. The excess material can be provided, for example, as a material reserve in the base region, in the wall region, in the flange region and/or in a transition region between flange region and wall region or wall region and base region. In particular in the event of compressing calibration of elongate profiles in the shape of a half shell, the pressing forces have hitherto frequently not been sufficient because of the comparatively long length. In addition, components of this type can be particularly advantageously divided into different regions and calibrated in a time-staggered manner. Alternatively, only one or more portions of the preshaped component is or are calibrated.

According to a preferred refinement of the method according to the first aspect, the preshaped component is calibrated at least in regions without trimming to form the finally shaped component. An additional trimming which is complicated in terms of plant technology can be dispensed with at least in sections because of the calibration provided of the preshaped component with compression at least in sections.

According to a preferred refinement of the method according to the first aspect, the calibration to form the substantially finally shaped component takes place in a tool or in different tools. If the calibration to form the finally shaped component takes place in a tool, the outlay on plant technology can be kept low. For example, the tool comprises different tool parts which are loaded and/or relieved of load in a time-staggered manner. During the calibration, for example, tool parts can be partially relieved of load, and therefore different regions of the preshaped component are calibrated in a time-staggered manner or alternatively only one or more portions of the preshaped component are calibrated. For example, the tool is configured for calibrating only one region of the preshaped component and, by means of a relative movement between component and tool and repeated closing of the tool, the component is gradually calibrated. If the calibration to form the finally shaped component takes place in different tools, one tool is configured, for example, only for the calibration of some of the different regions (for example only one region). This permits calibration which is in particular neutral in respect of cycle time.

According to a preferred refinement of the method according to the first aspect, component transport takes place between the calibration of different regions of the preshaped component to form the substantially finally shaped component. Transport within a tool or between different tools can take place. This makes it possible to keep the complexity and activation of the calibration tool low and to avoid the division into different tool parts.

According to a preferred refinement of the method according to the first aspect, the different regions which are calibrated in a time-staggered manner are component portions arranged along the preshaped component. For example, the regions are component length portions which are arranged next to one another in the longitudinal direction. By this means, an additional expenditure of time during the time-staggered calibration can be kept low.

According to a preferred refinement of the method according to the first aspect, during the calibration of a region, at least some of the remaining regions are secured against yielding. The effect which can be achieved by this is that the calibration action occurs as comprehensively as possible within the desired region. The securing can be achieved, for example, by at least partial fixing or supporting of at least some of the remaining regions which are specifically not being subject to any calibration.

According to a preferred refinement of the method according to the first aspect, the workpiece has a substantially homogeneous thickness and/or is produced from one material. By means of the time-staggered calibration, sufficiently high strength and/or rigidity can be achieved while at the same time the use of workpieces composed of different materials or having different sheet metal thicknesses (for example tailored blanks or patchwork blanks) can be dispensed with, which saves on working steps and therefore outlay and costs.

According to the first aspect of the present invention, the object is achieved in the case of a tool of the type in question in that the tool is configured to calibrate different regions of the preshaped component in a time-staggered manner or to calibrate only one or more portions of the preshaped component. As already explained, disadvantages mentioned at the beginning can therefore be eliminated or at least greatly minimized and the spectrum of use can be extended to components which, in particular with the boundary conditions of the method known from the prior art, were hitherto unable to be manufactured.

A preshaping tool can comprise in particular a (deep drawing) die and a (deep drawing) punch. Of course, other preshaping tools can also be used for producing a preliminary shape in a workpiece. A calibration tool can comprise in particular at least one calibration die and a calibration punch. The tool can comprise one or more preshaping tools and/or one or more calibration tools.

According to a preferred refinement of the tool according to the first aspect, the at least one calibration tool comprises a plurality of tool parts, and the tool is configured to at least partially relieve the calibration tool parts from load during the calibration, and therefore different regions of the preshaped component are calibrated in a time-staggered manner. Time-staggered calibration of different regions can thereby advantageously take place in one tool and without additional component transport. However, it is alternatively also possible to provide just one calibration tool which calibrates different regions of the preshaped component, for example by repeated closing. Similarly alternatively, a plurality of calibration tools can be provided. Alternatively, it is also possible for only one or more portions of the preshaped component to be calibrated.

According to a preferred refinement of the tool according to the first aspect, the tool furthermore comprises securing means which are designed to secure at least some of the remaining—preferably adjacent—regions against yielding during the calibration of a region. The calibration action in the regions to be calibrated can thereby be improved. For example, the securing means are designed in the form of a hold-down means or also in the form of a die and/or punch.

According to a second aspect of the present invention, the object mentioned at the beginning is achieved in the case of a method of the type in question in that one or more locally thickened regions are produced during the calibration.

For example, the one or more locally thickened regions are produced in a base region, a wall region and/or a flange region of the substantially finally shaped component. A thickened region is understood as meaning that the wall thickness in the thickened region is greater than in a surrounding region. For example, the wall thickness in the thickened region is greater than the wall thickness of the finally shaped component in the regions which are not thickened in a targeted manner. By means of the thickened regions, it is possible in the desired regions to achieve in particular stiffening and/or hardening, neutrally in respect of cycle time and neutrally in respect of costs, without having to make recourse to the complicated measures described at the beginning.

The second aspect is therefore presented as an alternative to the first aspect in order to be able to achieve high dimensional accuracy, rigidity and/or hardening of components with little outlay in terms of process technology.

According to a preferred refinement of the method according to the second aspect, one or more locally thickened regions extending along the finally shaped component are produced during the calibration. For example, locally thickened regions extending in a substantially strip-shaped manner are produced. By this means, stiffening of the substantially entire component can be achieved.

According to a preferred refinement of the method according to the second aspect, the excess material introduced into the preshaped component is adapted in order to produce the one or more locally thickened regions. It has been shown that all that is necessary in order to control the stiffening action is to adapt the excess material, i.e. local material reserves, in order to obtain a sufficient stiffening action. That is to say, in particular more excess material than previously is introduced since thickening is now not avoided but rather is used positively in a targeted manner.

According to a preferred refinement of the method according to the second aspect, the one or more locally thickened regions are hardened by the calibration. The thickened regions therefore not only reinforce the component by means of the presence of additional material, but additional hardening (for example cold hardening) takes place.

According to a preferred refinement of the method according to the second aspect, more excess material is introduced into the preshaped component than is required for the calibration. In a departure from the previous approach, more excess material is therefore intentionally introduced in order to provoke the production of locally thickened regions.

According to a preferred refinement of the method according to the second aspect, the excess material is collapsed in a rippled manner at the beginning of the calibration and, up to the end of the calibration, is hardened to form the one or the more locally thickened regions. If the excess material is provided and the calibration is carried out such that the excess material collapses in a rippled manner, the formation of the one or more locally thickened regions, in particular as strip-shaped regions, can be achieved in a simple manner.

According to the second aspect of the present invention, the object is achieved in a tool of the type in question in that the tool is configured to produce one or more locally thickened regions during the calibration. The tool can be configured here, for example, by means of corresponding geometrical adaptation of the calibration tool, for example a punch and/or a die of the calibration tool, to produce the thickened region.

With regard to further refinements of the method and of the tool of the first aspect, they can furthermore be combined with the method and/or the tool of the second aspect and respective refinements thereof and refined further. In a corresponding manner, with regard to further refinements of the method and of the tool of the second aspect, these can also be combined with the method and/or the tool of the first aspect and respective refinements thereof.

Furthermore, by means of the preceding and following description of method steps according to preferred embodiments of the method of the different aspects, it is also the intention for corresponding means for carrying out the method steps by means of preferred embodiments of the tool of the different aspects to be disclosed. Likewise, by means of the disclosure of means for carrying out a method step, it is the intention for the corresponding method step to be disclosed.

The invention will be explained in more detail below with reference to two exemplary embodiments in conjunction with the drawing, in which

FIGS. 1a-c show schematic illustrations of the calibration operation within the scope of an exemplary embodiment of a method according to the first aspect;

FIG. 2 shows a schematic illustration of a preshaped component with excess material within the scope of an exemplary embodiment of a method according to the second aspect; and

FIG. 3 shows a schematic illustration of a finally shaped component after the calibration of the preshaped component from FIG. 2.

FIGS. 1a-c show schematic illustrations of the calibration operation within the scope of an exemplary embodiment of a method according to the first aspect. To this end, FIG. 1a shows a calibration tool 1 of a tool for producing sheet metal components. The tool furthermore comprises a preshaping tool (not illustrated). The preshaping tool has been used to deform a workpiece (for example a blank) to form the preshaped component 2, wherein material which is excess at least in regions has been introduced into the preshaped component 2. In this case, the component 2 is a flangeless U-shaped component made from a steel material.

The calibration tool 1 serves for calibrating the preshaped component 2 to form an at least partially finally shaped component 2′ (cf. FIG. 1c ) using the excess material, wherein the preshaped component 2 is compressed at least in sections. The calibration tool 1 comprises a punch 1 a and a die 1 b.

The tool is configured to calibrate different regions of the preshaped component 2 in a time-staggered manner. Alternatively and not illustrated, just one or more portions in the preshaped component can be calibrated, with other adjacent portions not having to be calibrated. In this case, the component 2 is calibrated in three different regions 2 a, 2 b, 2 c in a time-staggered manner. The regions 2 a, 2 b, 2 c are component portions arranged in the longitudinal direction of the component 2. The calibration takes place here only by means of the tool 1.

First of all, the region 2 a is calibrated in a first pressing operation (FIG. 1a ). The preshaped and already partially calibrated component 2 is then transported in the longitudinal direction in the tool 1, such that the next region 2 b can be calibrated. The region 2 b is then calibrated by means of a second pressing operation (FIG. 1b ). The preshaped and already partially calibrated component 2 is then transported again in the longitudinal direction in the tool 1, and therefore the final region 2 c can be calibrated. The region 2 c is then calibrated by a third pressing operation (FIG. 1c ).

The preshaped component 2 is now a finally shaped component 2′ and can be entirely removed from the tool 1.

As a result, despite a pressing force being available only to a limited extent, the component 2 has been able to be completely calibrated and can be provided in particular without trimming and with sufficient strength. Alternatively, it is also possible for only one or more portions of the preshaped component to be calibrated.

FIG. 2 shows a schematic illustration of a preshaped component 3 with excess material 4 within the scope of an exemplary embodiment of a method according to the second aspect. The component 3 is a U-shaped component with a base region and wall region. Not only has excess material 4 been introduced into the base region of the preshaped component 3, but said excess material has also been adapted in order to produce one or more locally thickened regions 5. For this purpose, more excess material 4 is introduced into the preshaped component 3 than is required for the calibration.

If the preshaped component 3 is calibrated, the excess material 4 collapses in a rippled manner at the beginning of the calibration. Up to the end of the calibration (bottom dead center of the press, not illustrated), the excess material 4 is hardened to form a plurality of locally thickened regions 5.

The finally shaped component 3′ is illustrated in FIG. 3. The locally thickened regions 5 produced during the calibration extend along the finally shaped component 3′.

The methods illustrated in FIG. 1 and FIGS. 2, 3 can advantageously also be combined with one another. 

1. A method for producing sheet metal components, the method comprising: preshaping a workpiece to form a preshaped component, wherein material which is excess at least in regions is introduced into the preshaped component; and calibrating the preshaped component to form an at least partially finally shaped component using the excess material, wherein the preshaped component compressed at least in sections, and wherein different regions of the preshaped component are calibrated in a time-staggered manner.
 2. The method as claimed in claim 1, wherein the preshaped component is a component in the shape of a half shell.
 3. The method as claimed in claim 1, wherein the preshaped component is a flangeless component at least in regions or comprises a flange at least in regions.
 4. The method as claimed in claim 1, wherein the preshaped component is calibrated at least in regions without trimming to form the finally shaped component.
 5. The method as claimed in claim 1, wherein the calibration to form the finally shaped component takes place in at least one tool.
 6. The method as claimed in claim 1, wherein preshaped component transport takes place between the calibration of different regions of the preshaped component to form the finally shaped component.
 7. The method as claimed in claim 1, wherein the different regions which are calibrated in a time-staggered manner are component portions arranged along the preshaped component.
 8. The method as claimed in claim 1, wherein, during the calibration of a region, at least some of the remaining regions are secured against yielding.
 9. A tool for producing sheet metal components comprising: at least one preshaping tool for preshaping a workpiece to form a preshaped component, wherein material which is excess at least in regions is introduced into the preshaped component; and at least one calibrating tool for calibrating the preshaped component to form an at least partially finally shaped component using the excess material, wherein the preshaped component is compressed at least in sections, and wherein the tool is configured to calibrate different regions of the preshaped component in a time-staggered manner.
 10. The tool as claimed in claim
 9. wherein the at least one calibration tool comprises a plurality of tool parts, and the tool is configured in such a manner that the calibration tool parts arc partially relieved of load during the calibration, and wherein one of different regions of the preshaped component are calibrated in a time-staggered manner and only one or more portions of the preshaped component arc calibrated.
 11. The tool as claimed in claim 9, wherein the tool further comprises a securing device to secure at least some of remaining regions against yielding during the calibration.
 12. A method for producing sheet metal components, the method comprising: preshaping a workpiece to form a preshaped component, wherein material which is excess at least in regions is introduced into the preshaped component; and calibrating the preshaped component to form an at least partially finally shaped component using the excess material, wherein the preshaped component is compressed at least in sections, and wherein one or more locally thickened regions are produced during the calibration.
 13. The method as claimed in claim 12, wherein the one or more locally thickened regions extend along the finally shaped component and are produced during the calibration.
 14. The method as claimed in claim 12, wherein the excess material introduced into the preshaped component is adapted to produce the one or more locally thickened regions.
 15. The method as claimed in claim 12, wherein the one or more locally thickened regions are hardened by the calibration.
 16. The method as claimed in claim 12, wherein more of the excess material is introduced into the preshaped component than is required for the calibration.
 17. A tool for producing sheet metal components comprising: at least one preshaping tool for preshaping a workpiece to form a preshaped component, wherein material which is excess at least in regions is introduced into the preshaped component; and at least one calibrating tool for calibrating the preshaped component to form an at least partially finally shaped component using the excess material, wherein the preshaped component is compressed at least in sections, and wherein the tool is configured to produce one or more locally thickened regions during the calibration.
 18. The method as claimed in claim 1, wherein the preshaped component is U-shaped in cross-section.
 19. The method as claimed in claim 1, wherein the preshaped component is hat-shaped. 